Oswald cobadi and henri graf-buchler



Aug. 5. 1924a Re. 15,884 0. CORADI ET AL v menmrc cmfcx Original Filed July 8, 1920 A 8 3 1 H. H-.

Reisaued Aug. 5, 1924.

OSWALD COKADI AND HENRI GBAI-BUCHLER, OF ZURICH, SWITZERLAND.

MAGNETIC CHUCK.

Original No. 1,412,778, dated April 11, 1922, Serial No. 894,819, filed July 8, 1820. Application for reissue filed February 18, 1924. Serial llo. 693,445.

To all whom it may concern:

Be it known that we, OSWALD CoRAm, a citizen of the Re ublic of Switzerland, residing at Zurich, i Veinbergstrasse 49, Switzerland, and HENRI GnAr-BUonLns, a citizen of the Republic of Switzerland, residing at Zurich, Splugenstrasse 12, have invented certain new and useful Improvemeats in Magnetic Chucks, for which we have applied for a patent in Switzerland applicatmn Number 91 of date June 19, 1919, and in Germany application Number 028,161 of date July 2, 1919; and we do hereby declare the following to be a. clear,

16 full, and exact descri tion of the invention, such as will enable 0t ers skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

The hitherto known magnetic chucks and more particularly those used in holding pieces of work such as straight edges an the like on grindin machines present the disadvantage that t e parts of the chuck near its edges have no gripping power, so that the surface of a chuck cannot be utilized over its whole extent and a narrow 80- straight ed cannot be held firmly with suflicient orce. Furthermore with the known magnetic chucks a blank cannot be fixed to the lateral edge of the chuck whereby machining the blank is rendered more as diificult.

The object of the resent invention is a magnetic chuck in w ich the gaps between the of t e chuck from one side to the opposite side, whereby the above mentioned drawbacks are not only overcome but great advantages are attained consisting in the facts that an increased hOlding power can be obtained by increasing the sectional areas of 4a; the cores of the various magnets and that the magnetic action extends up to the edges of the chucks and to their lateral faces, thus enablin the machining of the blank not only on faces parallel to each other'but to; also on faces standing at right angles to each other which is of the greatest im-' rtance when machining straight edged limks.

Another object of the invention is to prolitivide a magnetic chuck formed of one inles extend entirely across the surface tegral member about portions of which the magnetlzlng coils are wound. For this purpose, we form the body member with a number of integral extensions, portions of whlch form the su ports for the coils and the end surfaces of which form the work engaging surface.

. Two exemplifications of the invent-ion are shown on the accompanying drawings, on which:

Figure 1 is an'elevation and Fi 2 a lplan view of part of a magnetic chuck in a rst exemplification;

Fig. 3 is a cross-section thereof;

Fig. 4 is a section through a second exexemplification, and

Fig. 5 is a sectional view of a portion of the chuck taken through the pole pieces.

In the Figs. 1-3 a base plate 1 is provided with a plurality of cores each fitted with a. coil 3 and a pole piece 2. The aps 4 between adjacent pole pieces 2 are lled by bars of a non-magnetic material 5. The pole pieces 2 and .the bars 5 are flush and form a chuck with a smooth surface.

The gaps 4 between adjacent ole pieces extend from one longitudinal e ge of the chuck plate to the other, whereby the whole surface of the chuck is magnetically effective up to its edges and up to'the lateral faces which are vertical to the surface of the plate. The lateral faces 6 are arranged in one common vertical plane with the lower faces 7 provided on the longitudinal edges of the base late '1, whilst the part of the base plate lying between the faces 6 and the face 7 and the covers 8 protecting the coils 3 are back of said faces 6 and 7.

The coils 3 may be manually wound about the intermediate portions of the integral projections or pole pieces 2. In this way, the magnetic paths within the chuck are entirely within a single member. The magnetic loss is therefore reduced to a minimum and the maximum magnetic force is applied to hold the work to the chuck. Also,

I the chuck is made up of fewer parts and is therefore simpler, stronger and less liable to get out of order.

In consequence of the extension of the gaps from one longitudinal side of the chuck to the other it is rendered possible to utilize the magnetic action. which is only efi'ective when two poles are bridged over by a blank of magnetic material up to the width 0 edges of the surface of thechuck. and its lateral faces. Pieces of work can thus be machined at right angles. The chuck is almost as effective at its vertical faces as it is at its horizontal surface.

In the exemplification illustrated in Fig. 4 the pole pieces are shaped to form two surfaces of the chuck at right angles to each other. The coil is also wound at an angle of 90 and the two surfaces of the chuck standing at right angles to each other are thus ener 'zed in the same degree. Both surfaces of Sic chuck may. be utilized for holding down pieces of work with the same effect. V

The aps that extend over the whole fthe chuck enable the ratio between the sectional areas of the cores and the surface of the chuck to'bemade as large as possible and it is evident that with the same degree of energizing of the core the holding .power of the chuck increases proportionally to the ratio between the cross sectional areas of the cores and the surface of the chuck. A chuck according tofthe invention produces in consequence of theincrease in the sectional areas of the cores a larger holding power without requiring more magnetizing energy than the hitherto "known constructions. V

In order to replace one working face of the chuck shown in Fig. 4 by the other the chuck is turned byan angle of 90by hand or any suitable device- The shape of the chuck is not limited to the rectangular crosssection but it may be any suitable one. o For instance, the chuck may be of circular forin having substantially radial slots extending to the outer periphery of the chuck. Any form in which the slots extend to the edges or periphery will have many of the advantages and be within the scope of the invention'. Y

What we claim is: I A 1. A magnetic chuck comprising a plurality of adjacent magnets having top faces and lateral faces, respectively in'planes at right angles to each other, the respective faces of each. magnet being spaced apart from the faces of any other magnet. I

2. In a magnetic chuck, a base plate, cores on said base plate, windings on said cores, pole pieces for said cores, said pole pieces having top faces and lateral faces, the

faces of each pole piece being spaced from the faces of any other pole piec'e.

3. In a magnetic chuck, a base plate, cores provided upon said base, p1ate,w1ndings on said cores, pole pieces having lateral workholding faces arranged side by side and spaced apart b gapsextending entirely across the chuc between opposite lateral faces, said pole pieces being flush to form horizontal and laterally :gapped working faces.

\ pieces spaced apart to form gaps extending to the extreme edges of the chuck.

5. In a magnetic chuck, a base plate, cores. on said base plate, pole pieces for the cores, each of said cores having faces at right angles to one another and gaps between the poles extending to said faces and entirely across the chuck to its extreme edges, said two faces adapted to replace one another by turning the chuck through an angle of ninety degrees.

6. In a magnetic chuck,cores having. pole shoes in one piece with the cores, windings on said cores, a base for the cores, the pole pieces having gaps between them terminating at the outer faces of the sides of the chuck, the edges of the cores lying in the same plane as the lower portion of said base. i

about said extensions whereby the magnetic paths within the chuck areentirely within a single member.

8. A magnetic chuck comprising in combination, a base, a plurality of integral extensions formed on one side thereof, and

coils wound about said extensions whereby the magnetic paths within the chuck are en'- tirely within a sin le member.

9. A magnetic c uck comprising in combination, a base, a plurality of integral extensions formed thereon, said extensions being spaced apart from'side to side of said chuck, and 0011s wound about said extensions whereby the magnetic paths within the chuck are entirely within a single member.

10. A magnetic chuck comprising in combination, a base, a plurality of integral extensions formed thereon, the ends of said extensions forming the work engaging-surface of the chuck, and coils wound about said extensions whereby the magnetic paths within the chuck are entirely within a single member. 7

11. A magnetic chuck comprising in com bination, a base, a plurality of integral extensions formed thereon and" extending from side to side of said base, the ends of said extensions forming the work engaging surfaces of the chuck, and coils wound about said extensions whereby the magnetic paths .within the chuck are entirely within a single member. a

12. A ma etic chuck comprising in combination, a ase, a plurality of integral extensions formed thereon, the ends of said extensions forming the work engaging surface of the chuck, inserts ofnon-magnetic material separating the extensions from-each other, and coils wound about the intermedi- 7 ate portions of the extensions.

13. A magnetic chuck comprising in combination,a base, a plurality of integral extensions formed along one surface thereof, the ends of said extensions forming the work engaging surface of the chuck, inserts of non-magnetic material separating the extensions from each other, and coils wound about the intermediate portions of the extensions.

14. A ma netic chuck comprising in combination, a ase, a plurality of integral extensions formed on one side thereof, coils wound about intermediate portionsof said extensions whereby the magnetic paths Within the chuck are entirely withln a single member, the end faces of said extensions forming the work engaging surface of the chuck.

15. A magnetic chuck comprising in combination, a base, a plurality of integral extensionsformed on one side thereof, coils wound about intermediate portions of said extensions whereby the magnetic paths within the chuck are entirely withm a single member, the end portions of said extensions being enlarged and their end faces forming the work engaging surface of the chuck.

In testimony whereof, we hereto aflix our slgnatures.

' OSWALD OORADI.

H. GRAF-BUCHLER. 

